The present application relates to dual fuel engines and controls for dual fuel engines, and more particularly, but not exclusively, to dual fuel engines with multiple cylinder banks and controls using cylinder bank fuelling cutout to increase gaseous fueling substitution under certain operating conditions.
Dual fuel engines have been developed to enable the use of gaseous fuel as a substitute for a liquid fuel, such as diesel fuel, under certain operating conditions. The gaseous fuel is typically lower in cost and readily available in applications where such engines are employed. In order to take advantage of the lower cost gaseous fuel, it is desirable to maximize the substitution rate of gaseous fuel for liquid fuel when operating conditions permit. However, various engine operating requirements dictate that a certain amount of liquid fuel be employed during operation. For example, injectors typically require a threshold amount of liquid fuel to be injected to maintain injector tip temperature below acceptable limits. In addition, a certain amount of liquid fuel is required to ignite the gaseous fuel. Thus, under light load or part load conditions encountered during light duty cycles, high substitution rates of gaseous fuel are not able to be achieved. In addition, exhaust aftertreatment system temperatures are required to be maintained above certain thresholds to enable effective operation of the aftertreatment components. Under light or part load conditions, minimum required fuelling to the cylinders may need to be increased above that required to meet demand torque in order to satisfy aftertreatment temperature requirements. Therefore, further improvements in this technology area are needed for exhaust aftertreatment system thermal management and/or to achieve greater substitution rates of gaseous fuel for liquid fuel in dual fuel engines under light or part load conditions.